Description of the Related Art
Prior disclosure relating to the present invention have been filed by one of the assignees of the present applications Japanese Utility Model Application No. 62-150087 (now Japanese Utility Model Kokai Publication No. 64-55339, laid-open on Apr. 5, 1989, which corresponds to the U.S. Pat. No. 4,899,617 filed on Sept. 30, 1988). According to this prior application, resilient members for preventing the generation of a knocking noise are provided over the entire surface of a spring seat in an apparatus for absorbing torque vibration having a similar construction to that of the present invention.
The object of the previous application is an arrangement such that the spring seat will not directly contact driving and driven disks when an engine, which is the driving source, is started and stopped, thereby preventing the generation of a knocking noise even if the torque vibration between the seat and each of the disks is large. The problem to be solved by the invention is as follows:
With the shock absorbing means illustrated in the related invention, the spring seat does not directly contact the driving and driven plates when the rotational speed of the engine is in a resonant rotational speed region of the torque vibration absorbing apparatus (i.e., when the engine is started and stopped), thereby preventing the occurrence of abnormal sounds in the torque vibration absorbing apparatus.
In a case where a large torque is applied to the torque vibration absorbing apparatus in the prior application described above, a large compressive force is conferred upon the resilient members interposed between the spring seat and the plates. Since the compressive force is large, there is the possibility that the resilient members will be damaged or sustain abnormal wear. In a case where the torque vibration absorbing apparatus rotates at high speed, contact occurs mainly at the outer peripheral side of the spring seats when the spring and the spring seats of the damper mechanism contact the arm portion of the driven disk. At this time, knocking noise is reduced owing to deformation of the resilient members affixed to the entire surface of the spring seat, but an offset, which is equivalent to the amount of deformation of the resilient members, occurs at the engagement between the spring seat and the arm portion of the driven disk, and therefore the spring flexes in a state tilted with respect to the central axis of the spring. As a result, the spring contacts the flywheels. Owing to this sliding resistance, the spring cannot deliver a sufficient restraining force and the possibility arises that vibration will not be sufficiently absorbed.